Method and apparatus for disinfection of a temperature control device for human body temperature control during extracorporeal circulation

ABSTRACT

The present application relates to a method for disinfection of a temperature control device for human body temperature control during extracorporeal circulation which temperature control is conducted by use of a heat exchanger and a temperature control liquid circulating through the heat exchanger and the temperature control device. According to the present application, the temperature control device is connected to a temperature control liquid supply and, during operation of the temperature control device for human body temperature control, a disinfectant is selectively added to the temperature control liquid supply upstream of the temperature control device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a national phase application of PCT Application No.PCT/EP2013/065602, internationally filed Jul. 24, 2013, which claimspriority to European Application No. 12 180 230.0, filed Aug. 13, 2012,all of which are herein incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a method for disinfection of atemperature control device, namely a heater and/or cooler system, forhuman body temperature control during extracorporeal circulation whichtemperature control is conducted by use of a heat exchanger and atemperature control liquid circulating through the heat exchanger andthe temperature control device and a corresponding heat exchangingsystem.

BACKGROUND

Extracorporeal circulation of blood is used in certain surgicalprocedures such as during heart surgery. During the extracorporealcirculation, the body temperature of the patient can be controlled, bycontrolling the temperature of the blood during extracorporealcirculation. For this purpose, a patient temperature control system canbe provided by means of which the temperature of the blood of thepatient in the circulation can be raised or lowered. The blood thuscontrolled, flows through the patient and the body of the patientapproaches the temperature of the blood. So as to heat or cool theblood, the temperature control system comprises a heater and/or coolerdevice providing a liquid circulation to a disposable (single use) heatexchanger that transfers energy to and/or away from the patient's bloodcirculation. The liquid can be water. The heat exchanger for the bloodis a strict dual circuit system/the blood side and the liquid side beingseparated from each other so that any mixture, such as by means ofdiffusion, between the blood in one of the circuits and the temperaturecontrol liquid in the other of the circuits is inhibited as much aspossible. Nevertheless, care has to be taken to avoid health risksstemming from the liquid.

SUMMARY OF INVENTION

The applicant has designed a mobile temperature control device for humanbody temperature control during extracorporeal circulation. Such amobile device can be connected to a circuit of temperature controlliquid to be used in a heat exchanger. The mobile temperature controldevice preferably is provided with exchangeable hoses or tubes or otherconduits. Further, connecting and disconnecting these conduits can moreeasily be achieved if the conduits are not filled with the temperaturecontrol liquid during connecting and disconnecting. Likewise, it ispreferred if the circuit can be emptied of temperature control liquidfor the connection and disconnection of the mobile temperature controldevice. The preferred mobile device is consequently provided with anopen reservoir where the temperature control liquid is exposed toenvironmental air. The temperature control liquid can be fed into thecircuit from this reservoir and can be returned to it. Any air whichmight be trapped in one of the conduits during connecting ordisconnecting the conduit and the temperature control device or the heatexchanger can be bled to the environment via the open reservoir. Thismeans, however, that the temperature control liquid is exposed to theair of the environment. Substances used as temperature control liquid,in particular water, are prone to microbial contamination when exposedto environmental air. If the temperature control liquid was exposed tothe environmental air, disinfecting the temperature control device andthe temperature control liquid can then improve the microbial status ofthe liquid and render the mobile device maintenance- andservice-friendly. It is usually necessary to manually conduct regulardisinfection procedures on the heater or cooler for the heat exchangerwhich are very time consuming and thus expensive.

The present invention addresses the necessity for regular manualdisinfection procedures of the temperature control device for theabove-identified technical field. Overcoming this necessity would resultin an improved efficiency of the temperature control device and thedisinfection of a temperature control device.

A heat exchanger for the human body temperature control using atemperature control device according to the present invention comprisesa blood side circulating blood and a temperature control liquid sidecirculating a temperature control liquid, wherein heat can be exchangedbetween the temperature control liquid on the temperature control liquidside and the blood on the blood side. In the heat exchanger, the bloodside and the temperature control liquid side are strictly separated fromeach other. The heat exchanger itself is a single-use device. After theoperation of the patient, the heat exchanger is disposed. However, thetemperature control device is a multi-use device and must be maintainedin a disinfected state. The temperature control liquid side of the heatexchanger is connected to a temperature control device for thetemperature of the temperature control liquid to be efficiently andreliably controlled. The temperature control device is a device which isconfigured for heating and/or cooling the temperature control liquid tobe introduced into the heat exchanger for human body temperature controlduring extracorporeal circulation.

According to the inventive method for disinfection of such a temperaturecontrol device for human body temperature control during extracorporealcirculation, the temperature control device is connected to atemperature control liquid supply and, during operation of thetemperature control device for human body temperature control, adisinfectant is selectively added to the temperature control liquidsupply upstream of the temperature control device. By connecting thetemperature control device to a temperature control liquid supply,temperature control liquid cannot only circulate in a closed loopsystem, but additional temperature control liquid can be added to thetemperature control device and, thus, also to the temperature controlliquid side of the heat exchanger. By selectively adding disinfectant tothe temperature control liquid supply upstream of the heater or cooler,i. e. the temperature control device, the disinfectant can effectivelybe added into the temperature control device and therefore disinfect thetemperature control device during operation for human body temperaturecontrol. This overcomes the necessity of an interruption of the use ofthe temperature control device which to date implies disconnecting thetemperature control device from the circulation system and disinfectingit remotely. Accordingly, the invention makes disinfecting thetemperature control device much more efficient. The temperature controlliquid supply can selectively supply additional temperature controlliquid to the temperature control device and preferably, if additionaltemperature control liquid is supplied, excessive temperature controlliquid is released from the temperature control device.

In connection with the present invention the term human means mammal orhuman and animal. It is to be noted that the inventive disinfectionmethod is completely conducted outside of the human or animal body.Preferably, the addition of the disinfectant is controlled by acomputer. The use of a computer facilitates automation of thedisinfection for it to be semi-automatic or fully automatic. Thisautomation includes dosing of disinfectant or mixing of severaldisinfectants to be added to the temperature control liquid. Such acomputer preferably comprises a user interface by which a user can setthe desired concentration and choice of disinfectants to be added to thetemperature control liquid. Further, it is possible that the computercontrols fully-automatic disinfection, in particular if a sensor, suchas a Clark sensor, is provided which measures the concentration ofdisinfectant in the temperature control fluid in the circuit. Theinformation from this sensor can be used by the computer for fullyautomatically controlling a method for disinfecting or maintaining adisinfection status of a circuit for extracorporeal circulationincluding the devices being part of this circuit such as a heatexchanger and a temperature control device. In particular, thedisinfectant comprises at least one of sodium hypochlorite, hydrogenperoxide and citric acid. These disinfection agents can be added to thetemperature control liquid either alone or in combination with eachother and further disinfectants. Use of one of these preferreddisinfectants ensures that disinfection can be conducted duringoperation of the temperature control device for human body temperaturecontrol. The preferred disinfectants are, under certain conditions inparticular, in specific ranges of concentration, not harmful to thehuman body, if the temperature control liquid should leak into the bloodof the patient via the heat exchanger or directly from the temperaturecontrol device or a connection tube, so that these disinfectants can, inmoderate concentrations, be used while the blood circulation takesplace. A disinfectant in connection with the described invention is adisinfecting substance which can be, and preferably is, permanentlypresent in the temperature control liquid without being hazardous to thepatient during extracorporeal circulation and without damaging a(plastic) heat exchanger or other part of the circuit for extracorporealcirculation. As long as the concentration of the disinfecting substancein the temperature control liquid is above a certain minimumconcentration/the substance is considered a disinfecting substance asthe circuit is then in a disinfected state. The disinfectant could alsobe called a “long term disinfectant” and can optionally be defined by amaximum concentration in the temperature control liquid. “Long term” isan individual period of time without a precise minimum or maximum. Anydisinfectant which, in its specific concentration in the temperaturecontrol liquid, can be used during the extracorporeal circulation andwhich does not require the circulation to be stopped for it being usedfor disinfection without being hazardous to the patient and withoutdamaging the heat exchanger or any other part of the circuit forextracorporeal circulation is considered a long term disinfectant in thesense of the present application. A preferable concentration of suchdisinfectant is below 500 mg/l, more preferably 300 mg/l or below butadvantageously 100 mg/l or above and/more preferably 200 mg/l orabove/or combinations of these ranges.

Preferably, the disinfectant is added by use of at least oneelectronically controlled liquid valve. Such a liquid valve enables anautomation device such as a computer to control the addition ofdisinfectant autonomously. Particularly the temperature control liquidincludes water and preferably consists of water 1 the long termdisinfectant and unavoidable contaminants. Since water is usually readyavailable in the required quality and quantity in many places, usingwater as the temperature control liquid is preferred. In the presenttext, the term “water” means “drinking water”. This implies astandardized quality and cleanliness of the water which is sufficientfor using the water as temperature control liquid in a heat exchangerand a corresponding temperature control device for human bodytemperature control during extracorporeal circulation. Further, water iscompatible with many long term disinfectants and, hence, allows forchoosing the disinfectant from a large group of potential long termdisinfectants. However, also other substances which differ from watercan be used as temperature control liquid. An inventive heat exchangingsystem for human body temperature control during extracorporealcirculation comprises the temperature control device described above anda disinfecting device connected to the temperature control device on anupstream side thereof via a temperature control liquid supply. Thisdisinfecting device is configured for selectively adding a long termdisinfectant to the temperature control liquid supply during operationof the temperature control device for human body temperature control.The disinfecting device can preferably be a dedicated separate apparatuswhich can be connected to the temperature control liquid supply, forexample fresh water supply, as well as to the waste liquid sink, forexample waste water sink. Alternatively, the disinfecting device canalso be integrally formed with the temperature control device. Inparticular/the disinfecting device comprises a computer controlling theaddition of disinfectant to the temperature control liquid. Thiscomputer is preferably provided with a user interface in order to setdesired properties for the addition of disinfectant to the temperaturecontrol liquid. The computer can preferably control an electronic valvein order to control the addition of disinfectant. Further preferred isif the disinfecting device comprises more than one electronicallycontrolled liquid valves in order to control the addition of a mixtureof several disinfectants to the temperature control liquid. The longterm disinfectant preferably comprises one of sodium hypochlorite,hydrogen peroxide and citric acid as mentioned before and, as is furtherpreferred, the disinfecting device may comprise several containers, eachfor one of a respective long term disinfectant so that the disinfectantscan be mixed in the disinfecting device and added to the temperaturecontrol liquid as a mixture. Such a mixture can be tailored to therequired disinfection procedure applied to the temperature controldevice. According to a preferred embodiment, the heat exchanging systemis configured for conducting the inventive method described before anddefined in the claims. Reference is made to the co-assigned patentapplication EP 12 180 231.8 filed on Aug. 13, 2012, entitled “Method forcontrolling a disinfection status of a temperature control device forhuman body temperature control during extracorporeal circulation”, thecomplete content of which is hereby incorporated herein. The co-assignedpatent application describes and claims a method for controlling adisinfection status of a temperature control device for human bodytemperature control during extracorporeal circulation which uses a longterm disinfectant. The method and the device described in the coassignedpatent application can preferably be combined with the inventiondescribed in the present application, in particular in that the additionof disinfectant to the temperature control liquid described in thepresent application can be based on the method and device disclosed inthe co-assigned patent application. In other words, the method anddevice disclosed in the co-assigned patent application can be combinedwith the invention disclosed in the present application. Thisparticularly facilitates performing a fully-automatic or at leastsemi-automatic disinfection method based on the information obtained bythe method and/or device of the co-assigned application. In particular,the outcome of the method for controlling the disinfection status of atemperature control device of the co-assigned application can be thatthe disinfection status of the temperature control device isinsufficient. In this case, the method of disinfection as described inthe present application can be used for improving the disinfectionstatus of the temperature control device, preferably semiautomaticallyor fully-automatically.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic view of the disinfecting device for a preferredheat exchanging system.

FIG. 2 illustrates the function of a preferred disinfecting device for apreferred heat exchanging system.

DETAILED DESCRIPTION

FIG. 1 shows a schematic illustration of a disinfecting device 10 for aheat exchanging system. The disinfecting device 10 comprises a tap watersupply 11 and a waste water drain 12 for connecting the disinfectingdevice 10 to an external supply/sink of temperature control liquid, inthis case water. The disinfecting device 10 further comprises a heaterand/or cooler supply 13 and a heater and/or cooler drain 14 throughwhich the disinfecting device 10 can be connected to a temperaturecontrol device, namely a heater and/or cooler (not illustrated). Theillustrated embodiment comprises one set of supply 13 and drain 14 foreither a heater or a cooler; if a heater and a cooler is to be used,then the device may comprise a single set or two sets. The watersupplied via the tap water supply 11 is guided through a filter system15 in order to further clean the water supplied to the disinfectingdevice 10. The disinfecting device 10 further comprises a firstdisinfectant container 16 and a second disinfectant container 17 whichcontain different long term disinfecting agents such as sodiumhypochlorite, hydrogen peroxide or citric acid for decalcification. Thedisinfecting agents of these containers 16, 17 can selectively be mixedand added to the water supplied to the disinfecting device 10 throughthe tap water supply 11. The mixture of the disinfecting agent and thetap water can then be circulated through the heater and/or cooler supply13 into the heater and/or cooler. The disinfecting device 10 furthercomprises a control display 18 by which a user can influence the settingfor the disinfection procedure conducted by the disinfecting device 10.For the user to be able to remotely control the disinfecting device 10,the disinfecting device further comprises a remote control terminal 20through which a remote control can be connected to the disinfectingdevice 10. In order to facilitate refilling or exchanging thedisinfectant containers 16, 17, the disinfecting device 10 is providedwith a housing having an opening which is normally closed by a lid 19.Opening the lid allows for accessing the interior of the housing of thedisinfecting device 10 and either refilling the disinfectant containersor exchanging them.

FIG. 2 illustrates the function and operation of the disinfecting deviceshown in FIG. 1 and like elements of the disinfecting device 10 in FIG.1 are assigned like reference signs also in the schematic view of FIG.2. The tap water supplied via the tap water supply 11 is led through thefilter 15 and through a first control valve 21. A flow meter 22indicates the liquid flow into the disinfecting device 10. Behind theflow meter 22, the duct guiding the water through the disinfectingdevice 10 continues into three parallel ducts, each provided with flowcontrol valves 21. A first duct A passes water through the disinfectingdevice 10 directly to the heater or cooler supply terminal 13 so that nodisinfectant is added to the water. A second duct B passes water throughthe first disinfectant container 16 by means of which a firstdisinfecting agent, e.g. sodium hypochlorite, is added to the water. Thewater can be passed through a portion of the container 16 which containsa predetermined amount of the first disinfecting agent of apredetermined concentration. The water passing through the firstdisinfectant container 16 then includes the disinfecting agent.Alternatively, the disinfecting agent can be injected into the waterpassing through the first disinfectant container 16 so that the waterobtains a predetermined concentration of a predetermined firstdisinfecting agent. Behind the first disinfectant container 16, a returnvalve 23 allows for letting the water including disinfectant flow to theheater and/or cooler via the heater and/or cooler supply terminal 13 butprevents any backflow reversely into the second duct B. A third duct Chaving basically the same structure as the second duct B is provided forthe second disinfectant container 17 comprising e.g. hydrogen peroxide.The design of ducts A, B and C permits, depending on the water flowcontrol valves 21, to either bypass water past the disinfectantcontainers 16, 17 and thus to add pure water, i.e. water in the samequality and composition as supplied via the tap water supply, to theheater and/or cooler, or to selectively pass the supplied water throughone or both of the disinfectant containers 16, 17 containing differentdisinfectants in order to add one disinfectant or a mixture of the twodisinfectants to the water to be supplied to the heater and/or cooler.Naturally, the invention is not limited to the preferred embodimentsdescribed before and in particular the number of disinfectant containersand ducts in the disinfecting device can be chosen in accordance withthe necessary supply water treatment.

The invention claimed is:
 1. A method for disinfecting a temperaturecontrol device for human body temperature control using a heat exchangerduring extracorporeal circulation, the method comprising: causing atemperature control liquid to circulate through the temperature controldevice, wherein the temperature control device is configured to regulatetemperature of the temperature control liquid; and selectively adding atleast a first disinfectant to the temperature control liquid duringoperation of the temperature control device during the extracorporealcirculation, based upon a first sensed concentration of the at leastfirst disinfectant in the temperature control liquid.
 2. The method ofclaim 1, wherein the addition of the at least first disinfectant iscontrolled by a computer.
 3. The method of claim 1, wherein the at leastfirst disinfectant comprises at least one of sodium hypochlorite,hydrogen peroxide and citric acid.
 4. The method of claim 1, wherein theat least first disinfectant is added by use of at least oneelectronically controlled liquid valve.
 5. The method of claim 1,wherein the temperature control liquid includes one or more of water,the disinfectant and unavoidable contaminants.
 6. The method of claim 1,comprising selectively adding at least a second disinfectant to thetemperature control liquid during the operation of the temperaturecontrol device during the extracorporeal circulation.
 7. The method ofclaim 6, comprising controlling valves by a computer to selectively addthe at least first disinfectant and the at least second disinfectant tothe temperature control liquid during the operation of the temperaturecontrol device during the extracorporeal circulation.
 8. The method ofclaim 1, comprising controlling valves by a computer to selectivelyprovide water, the at least first disinfectant, and at least a seconddisinfectant to the temperature control liquid during the operation ofthe temperature control device during the extracorporeal circulation. 9.The method of claim 1, comprising controlling valves by a computer toselectively provide water, the at least first disinfectant, at least asecond disinfectant, and at least a third disinfectant to thetemperature control liquid during the operation of the temperaturecontrol device during the extracorporeal circulation.
 10. A heatexchanging system for human body temperature control duringextracorporeal circulation, comprising: a temperature control deviceconfigured to regulate temperature of a temperature control liquidcirculated through a temperature control liquid side of a heat exchangerfor conducting the human body temperature control; and a disinfectingdevice connected to the temperature control device and configured toprovide the temperature control liquid to the temperature controldevice, the disinfecting device configured to selectively add at least afirst disinfectant to the temperature control liquid during operation ofthe temperature control device during the extracorporeal circulation,based upon a first sensed concentration of the at least firstdisinfectant in the temperature control liquid.
 11. The heat exchangingsystem of claim 10, wherein the disinfecting device comprises a computercontrolling addition of the at least first disinfectant to thetemperature control liquid.
 12. The heat exchanging system of claim 10,further comprising at least one electronically controlled liquid valveconfigured for adding the at least first disinfectant to the temperaturecontrol liquid.
 13. The heat exchanging system of claim 10, wherein thedisinfecting device is configured to selectively add at least a seconddisinfectant to the temperature control liquid during the operation ofthe temperature control device during the extracorporeal circulation.14. The heat exchanging system of claim 13, wherein the disinfectingdevice includes valves configured to be controlled by a computer toselectively add the at least first disinfectant and the at least seconddisinfectant to the temperature control liquid during the operation ofthe temperature control device during the extracorporeal circulation.15. The heat exchanging system of claim 10, wherein the disinfectingdevice includes valves configured to be controlled by a computer toselectively provide water, the at least first disinfectant, and at leasta second disinfectant to the temperature control liquid during theoperation of the temperature control device during the extracorporealcirculation.
 16. The heat exchanging system of claim 10, wherein thedisinfecting device includes valves configured to be controlled by acomputer to selectively provide water, the at least first disinfectant,at least a second disinfectant, and at least a third disinfectant to thetemperature control liquid during the operation of the temperaturecontrol device during the extracorporeal circulation.